Field of the Invention
The described technology relates generally to a frame supporting a unit mask used while depositing an organic emission layer and a mask assembly having the same.
Description of the Related Art
A display device is a device for displaying an image, and recently, an organic light emitting diode display has received attention. Unlike a liquid crystal display device, the organic light emitting diode display has a self-emission characteristic and does not require a separate light source. As a result, a thickness of an organic light emitting diode display can have a reduced thickness and weight. Further, the organic light emitting diode display has high-grade characteristics such as low power consumption, high luminance, and a high response speed.
In order to manufacture the organic light emitting diode display, an electrode having a predetermined pattern and an organic emission layer need to be formed, and a deposition method using a mask assembly may be applied as a forming method thereof. In more detail, the organic light emitting diode display has a configuration in which pixels, which are basic units for displaying an image on a substrate, are arranged in a matrix form. In each pixel, an organic light emitting diode, in which a first electrode as a positive electrode and a second electrode as a negative electrode, are sequentially formed with respective organic emission layers therebetween emitting red light, green light, blue light, and white light. Here, since the organic emission layer must be completely isolated from moisture in a process of forming the organic emission layer as well as after forming the organic emission layer, and because the organic material forming the organic emission layer is very vulnerable to moisture, oxygen, and the like, it is difficult to perform patterning by using a general photolithography technique. Accordingly, the organic emission layer is formed by using a mask with an opened pattern part where deposition material passes through only a portion corresponding to each pattern.
Recently, a mask assembly including a frame having openings and a plurality of band-shaped unit masks of which both ends are fixed to the frame in response to the openings has been used. Since a known mask assembly is supported by the frame by applying tensile force in a longitudinal direction of the unit mask, there was a problem in that the frame is unintentionally deformed by the tensile force applied to the unit mask in the longitudinal direction.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology, and therefore it may contain information that does not constitute prior art as per 35 U.S.C. §102.